For owners of cars with diesel engines (Mazda Capella GE)

If you're considering switching to diesel but don't know how to care for it yourself, we'll tell you right away that keeping a diesel engine in good condition is no more difficult than maintaining a gasoline engine...

Diesel vehicles are renowned for their durability, but that doesn't mean they don't require maintenance.

Prices for used diesel cars in the West are falling. This is due to the fact that for a long time the sales volume of new diesel cars was very high and therefore there are now a large number of them on the used car market. New diesel cars are much more expensive than their equivalent petrol counterparts. Moreover, the time has passed when the diesel range we are accustomed to today was limited to just one model. Today, manufacturers are able to supply the market with diesel engines that meet the highest requirements.

It is a pity that countries, if there are any, have diesel fuel that costs the same as petrol or even more. But even then, you'll still benefit from diesel cars, which tend to have a longer lifespan, as long as you drive a lot of mileage each year. No savings are achieved only with low annual mileage. You save on spark plugs, although it is clear that when using spark plugs with a replacement frequency of 60 thousand km, the savings on them will be small. At the same time, you will lose out on more frequent oil and filter changes.

What is attractive about diesel?

Modern diesel cars are attractive because of their ability to develop high traction force at low revs, which makes them especially good for drivers who don't like to change gears too often. Most manufacturers offer turbocharged diesel engines to give the owner the opportunity to experience the full charm of a high-end car.

If you're considering switching to diesel but don't know how to care for it yourself, we'll tell you right away that keeping a diesel engine in good condition is no more difficult than keeping a gasoline engine in good condition, despite their differences. We offer you a brief guide to purchasing, operating and maintaining a diesel engine.

The mechanisms of gasoline and diesel engines are not much different. Both engines operate on a four-stroke fuel combustion cycle, but they do so in completely different ways.

While gasoline engines ignite the air-fuel mixture with spark plugs, diesel fuel is ignited by very high compression.

While a gasoline engine draws in air and gasoline on the first stroke, a diesel engine draws in only air, which is compressed to such an extent that its temperature rises to 800°C. The hot air ignites the diesel fuel, which is injected into the cylinder's combustion chamber shortly before the piston reaches the bottom of the cylinder on the compression stroke. Because diesel engines have twice the compression ratio of gasoline engines, the fuel must be injected under very high pressure to force it into the combustion chamber and maintain the shape of the fuel jet. Due to the increased injection requirements, the diesel high-pressure fuel pump is a particularly precision-manufactured component.

Why is the diesel engine noisy?

The familiar roar of a diesel engine is caused by the combustion of fuel and the subsequent sharp drop in high pressure in the combustion chamber. The most clearly audible specific diesel rumble is heard after starting and while the engine is warming up at idle speed.

The diesel engine does not have an ignition system, but it does have a pre-heating system for the combustion chambers of the cylinders using starting spark plugs. In addition, the days of prolonged cranking of the engine with the starter and agonizing waiting for the indicator light to go out before starting the engine warms up are long gone. Many manufacturers are already producing quick-starting diesel engines that take no more than a couple of seconds to start in winter. Some cars even have a "starter handle" that can directly control the high-pressure fuel pump to vary injection timing, speed up warm-up, and reduce smoke emissions during start-up.

Diesel engine maintenance

Because diesel engines contaminate the oil in the lubrication system faster than gasoline engines, most vehicle manufacturers require more frequent oil and filter changes.

Special diesel oils are widely available today and, judging by reviews, are quite effective. However, any high-quality motor oil for carburetor engines is also suitable for diesel engines, as long as it is changed at certain intervals. Read the label on the can, where the manufacturer usually provides instructions for diesel engines. If you don't find anything on this label, look at the label on the container the jars were packed in.



On overhead camshaft engines, the timing belt should be replaced at the specified intervals. Otherwise, it is possible that the piston will collide with the valves when the belt suddenly breaks. Eliminating the consequences of the latter will require considerable financial expenditure from you. In practice, there have already been cases of belt breakage with a mileage of up to 48 thousand km, but this occurred as a result of oil or water getting on them due to depressurization of the lubrication and cooling systems, respectively. However, if you decide to continue driving without changing the belt after 58,000 km, your reluctance to take the time to replace it in a timely manner could result in significantly greater time and money costs in the future.

When replacing your fuel filter, buy the best one available to you. Some filters may look good but perform poorly. Don't forget to replace the O-ring on the filter housing. It should also be noted that on a diesel engine, it is equally difficult to prevent both fuel leaks and air suction into the fuel system, which significantly disrupt engine operation.

If air gets into the fuel lines, it may be necessary to remove it from there through a special valve using a small hand pump, usually mounted for this purpose on the high-pressure fuel pump. Many modern diesel engines have fuel systems that self-bleed air. You just need to turn the engine with the starter and the air will be removed.

It is difficult to prevent moisture from condensing in the fuel filter, so some diesel engines are equipped with a warning light on the instrument panel to indicate the presence of water in the fuel system.



Typically, when changing the oil, you only need to check the condition of the filter. However, if the vehicle is operated in severe conditions, such as high humidity and large differences between day and night temperatures, the condition of the filters should be checked more frequently.

All diesel engines smoke when cold, but it shouldn't be excessive. One of the most common reasons for this is a failure in the timing of fuel delivery by the high-pressure pump, which is easily corrected by re-adjusting the injection timing using the marks on the crankshaft and pump. This work is very similar to adjusting the initial ignition timing on a gasoline engine. The operation can be performed with the engine off, but it is better to purchase a special lamp for setting the injection timing on diesel engines. This lamp is attached with a clamp to the fuel supply line of the injector and lights up under the action of the fuel impulses passing through the line.

Another cause is fuel leakage through injectors with a loosely sealed fuel supply channel, which can lead to overfilling of the cylinder with fuel and, as a consequence, to excessive smoking during start-up. Apart from a general cleaning of the injectors and replacing worn ones at around 110,000 km, there's little you can do at home to check their operation. Unless you take them off and have them checked on some kind of testing equipment.

New injectors aren't cheap, but you can save a significant amount by going to a diesel repair shop and having your injectors calibrated for a very reasonable price. The price of the service depends on the location of the station and the availability of spare parts stores around it.



However, you can extend the life of your injectors by keeping your diesel intake air and fuel filters clean, thereby preventing injector fouling. For these purposes, you should periodically pour a small amount of special cleaners into the fuel tank.

If you take care of your high-pressure fuel pump, it will function properly for a long time. However, we would like to warn you that replacing it is quite an expensive undertaking.

Poor starting and poor throttle response in a diesel engine can be caused by many things: poor-quality spark plugs, clogged fuel lines that cause a drop in fuel pressure, faulty fuel lines, and even improperly installed injectors. It is easy to identify poorly functioning spark plugs by how long the pre-heating indicator light stays on.

The following table of possible diesel engine defects has been compiled by Bosch, and we hope that it will help you return your engine to working order.

Talk to diesel car owners and you'll find that none of them would even consider driving a petrol car again. Perhaps it's your turn if diesel meets your needs perfectly.

Diesel engine malfunctions with Bosch fuel injection equipment

The following table of possible diesel engine defects has been compiled by Bosch, and we hope that it will help you return your engine to working order.

Table of malfunctions and methods for their elimination on diesel engines with Bosch fuel injection equipment

Malfunction	Possible cause codes
Difficult start	1–9, 12, 13, 20, 22
Unstable idle	1, 2, 14, 18, 21, 22
Uneven idle speed of a warm engine	2, 10, 13, 17, 20, 22
Engine misfires under load	1, 2, 4, 5–10, 16, 22
Engine power loss	1, 4–7, 9, 10, 11, 13, 15, 16, 19–22
Increased fuel consumption	7, 9, 10, 11, 13, 15, 16, 19–22
The engine does not stop	3, 21, 22
Poor throttle response, black smoke from the exhaust, loss of engine power	2, 5, 9, 10, 11, 13, 19–22
Blue exhaust at maximum load (white or blue)	1, 2, 4, 5, 8, 9, 13, 19, 22
Abnormal minimum and maximum idle speed	14, 15, 18, 21
The engine does not accelerate	1, 2, 4, 6, 8, 9, 10, 19, 20, 21
The high pressure fuel pump is overheating	16

Malfunction	Methods of elimination
1. Empty fuel tank or clogged fuel tank vent valve	Fill the tank, flush the fuel lines, clean the ventilation valve.
2. Presence of air in the fuel system	Bleed the fuel system, eliminate air leaks.
3. The diesel solenoid valve or starting fuel supply regulator is faulty	Repair or replace.
4. The fuel filter is clogged	Replace the fuel filter.
5. Low pressure fuel lines are clogged	Restore the flow cross-sections of the fuel lines.
6. Low pressure fuel lines are clogged	Flush or replace fuel lines.
7. Loose connections, leaking or broken fuel lines	Tighten the connections, eliminate the leak.
8. Paraffin deposits in the fuel filter	Replace filter, use seasonal fuel.
9. Incorrect fuel injection advance	Adjust the initial fuel injection advance angle.
10. The injector nozzles are faulty	Repair or replace.
11. The air filter is clogged	Replace the filter element.
12. The pre-heating system is faulty	Replace faulty spark plugs.
13. The injection distribution among the cylinders does not correspond to their firing order	Rearrange the high pressure fuel lines in the required order.
14. Abnormal idle speed	Adjust the idle speed with the screw.
15. Abnormal maximum idle speed	Adjust the maximum engine speed with the screw.
16. The bypass valve is clogged or faulty	Clean the calibrated channel or replace the valve.
17. The discharge valve is leaking (on a four-cylinder diesel engine) or two valves (on a six-cylinder)	Replace the valve.
18. The force of the buffer spring of the diesel engine speed regulator is not adjusted	Adjust the buffer spring force.
19. The fuel injection advance clutch is faulty	Repair or replace the coupling.
20. Low compression	Restore compression.
21. The engine speed controller is faulty or not adjusted	Adjust or replace the regulator.
22. The high-pressure fuel pump is faulty or cannot be adjusted	Remove the pump and send it for repair.

Buying a used engine

Be careful when buying a used diesel engine. Diesel engines last a long time, but that doesn't mean you shouldn't inspect all the traditional wear and tear areas. On some engines, it is very easy to disguise both age and wear. When assessing the condition of such an engine, there is a risk of "failing" if you do not understand diesel engines well.

Like petrol engines, diesel exhaust must be smokeless. In addition, there should be no smoke coming out of the open neck of the oil filler tube on a warm engine. Since diesel engines are typically noisier than gasoline engines, you should distinguish between normal operating noise and the knocking of worn pistons, connecting rods, camshafts, etc. If you have any doubts about the engine's condition, seek professional help.

Turbo diesels are very popular because turbocharging fits well with the characteristics of a diesel engine. Turbochargers operate with low boost pressure and at low engine speeds, which gives them a longer service life than gasoline engines. Turbo diesel engines are ideal for tractors and multi-ton trucks.

The article is copied from the website mazbook.ru

However, diesel automatic transmissions have difficulty meeting the demands of an automatic transmission due to the flat torque curve. Few manufacturers are concerned about this problem. These include Citroen, Mercedes, Peugeot and, recently, Opel, but even they only use automatic transmissions in mid-range cars.

Thanks to their ever-increasing popularity, diesels are no longer looked upon as the poor cousin, and are now fully on par with their petrol counterparts in terms of quality.

When purchasing, pay attention to the residual value of diesel. Diesel cars once gave a boost to car sales in Germany, but sales peaked four years ago and have been in gradual decline ever since, so make sure you're not overpaying for the privilege of owning a diesel car.

Check the mileage. Diesel cars are sought after for their potential for high reliability and potentially high mileage. Especially when they are bought new. But this doesn't mean you shouldn't pay attention to the odometer. Indeed, many dealers dislike dealing with cars with mileage exceeding 80,000 km and, accordingly, adjust their prices. Or, without further ado, they simply reset the mileage on the counter. A mileage of 160,000 km is quite normal for a well-maintained diesel, but think twice if the odometer shows 320,000 km, or especially if it is a used taxi with such mileage.

With the exception of the engine, most diesel cars are identical in design to their petrol counterparts, the same applies to suspension and brakes, but keep in mind the cost of spare parts. For example, exhaust systems last a long time, but differ from similar gasoline engines. If you're used to buying parts from salvage dealers, keep in mind that while gasoline engine parts may look similar and fit, the cylinder block of a diesel engine is different from that of a gasoline engine and, in most cases, cannot be used as a replacement. The gear ratios of gearboxes and clutches also differ.

Be healthy diesel

The engine sputtered once, twice, and then died... Anyone who's been in this situation probably knows the swarm of questions that race through their minds during unsuccessful attempts to restart the "heart" of their "iron horse." Owners of diesel-powered cars are no different from everyone else, but the causes of diesel engine problems and their solutions are largely specific to this type of engine. To avoid making your life more difficult, it's best to listen to the advice of professionals with extensive experience in this field.

We turned to them again this time, and found a wealth of useful information and practical advice that was quite easy to implement.

The biggest surprise is that the engine, which was causing no problems just yesterday, suddenly refuses to come to life at the very moment when you are rushing to work in the morning. If this is the first time this has happened, and is accompanied by white exhaust, then it is almost certain that the glow plugs are to blame. By the way, the indicator on the instrument panel may well be wrong, claiming that the spark plugs are OK. To check, connect one end of the wire to the positive battery terminal, and the other end supplies voltage directly to the spark plugs. If a good spark jumps through (it is easy to distinguish from the bright flash of a short circuit), the wire starts to heat up, and after that the engine starts, then the spark plugs have nothing to do with it. The problem should be looked for in the electrical circuits that supply voltage to them. In this way, you can also check the fuel supply valve.

And finally, you only have yourself to blame if you tried to start the car straight away before. The timing belt could easily slip through several teeth. The engine won't start and you may need to prepare for a complex and expensive engine repair.

Experience shows that another very common situation is when the engine is idling, and when you try to increase the speed, it immediately stalls or stops after running for a short time. Most likely, air has entered the fuel system. It is worth paying attention to the exhaust again. In this case, it is usually white with a characteristic smell of diesel fuel. A vacuum in the fuel flow can occur due to a blockage, say, in the fuel intake or fuel filter. Most often, it is the fuel filter that gets clogged, and such problems mostly occur in winter.

Experience shows that another very common situation is when the engine is idling, and when you try to increase the speed, it immediately stalls or stops after running for a short time. Most likely, air has entered the fuel system. It is worth paying attention to the exhaust again. In this case, it is usually white with a characteristic smell of diesel fuel. A vacuum in the fuel flow can occur due to a blockage, say, in the fuel intake or fuel filter. Most often, it is the fuel filter that gets clogged, and such problems mostly occur in winter.

Technodiesel specialists advise everyone to adhere to a rule that has no exceptions: never repair fuel filters. Various "rinses", "blowings," and other supposedly restorative procedures will, at best, simply have no effect, and at worst, will worsen the situation. Fuel passing through such a "regenerated" filter not only does not receive the required cleaning, but also washes away all the dirt that had previously accumulated in the filter. This can quite quickly disable the precision mechanism of the fuel injection pump.

Another pseudo-help for the engine that "knowledgeable" mechanics like to provide is the installation of several fuel filters. From the point of view of achieving unprecedented purity of diesel fuel entering the engine, there is no point in this multi-stage filtration. Diesel vehicle manufacturers carry out precise calculations of filter performance, which are confirmed by extensive testing, so they are worth trusting. Additional filters are not only useless, but harmful. They create unnecessary resistance, causing the fuel injection pump to overload and fail faster. Increased resistance in the pipeline can also cause air to be sucked in.

You shouldn't be led by another fairly common misconception that additional filters help separate water from fuel. In fact, filters do not retain water; there are special separator tanks for this purpose. The presence of such a separator is indicated by a small plug at the bottom under the filter. The accumulated moisture should be drained approximately every 3000 km. You need to drain the liquid until almost pure diesel fuel flows out.

The presence of water in the fuel also causes white clouds in the exhaust gases. Some modern diesel vehicles have an indicator on the dashboard that will tell you if there is water in the fuel. If the indicator lights up, it is better to stop immediately, turn off the engine and drain the liquid from the separator. If necessary, the procedure can be repeated. If the indicator still does not go out after this, then there is probably a problem in the electrical circuits of the water-in-fuel indicator system. You shouldn't try to fix anything quickly; it's better to take it to a car repair shop.

It also happens that a steadily humming engine suddenly, for no apparent reason, goes silent. The most trivial piece of advice, which, oddly enough, helps in many "difficult" cases, is to make sure there is still diesel fuel in the tank. If the situation is worse, and something really happened, it is worth remembering whether there was any sharp sound before the engine died. This sound is accompanied by a break in the timing belt. If so, it is better not to try to crank the engine - the consequences can be disastrous.

Another reason for a sudden engine stop could be the same air in the fuel system. You can try directly connecting the fuel pump to any container with diesel fuel. If the engine starts working, then the cause has been found. For any problems with the fuel pump, it is best to contact specialists rather than entrust repairs to dubious mechanics.

Once the fuel injection pump has been ruled out as a possible culprit, you can try loosening the fittings on the injectors. If, when attempting to start the engine, diesel fuel begins to flow out from under them in a pulsating stream, this means that faulty injectors are not ensuring a normal flow of fuel into the combustion chambers. You may notice black smoke coming out of the exhaust – this is one of the signs that the needle is stuck in the injector. Fuel begins to flow uncontrollably into the cylinder, and black exhaust is caused by incomplete combustion.

And one more thing – don't drive recklessly through deep puddles. Mechanics often see diesel engine damage from such bathing. Water from a puddle gets into the combustion chamber, and the powerful hydrodynamic shock bends even the strongest connecting rods!